[Twisted-Python] Looking for a simple file event driven loop using Twisted

[Dave Cook]

Using Ken's first example, here's what I came up with:

import os
import stat
from twisted.internet import reactor

class FileWatcher:

    def __init__(self, period, filename):
        self.period = period
        self.filename = filename
        self.callbacks = []
        self.mtime = os.stat(filename)[stat.ST_MTIME]
        reactor.callWhenRunning(self.checkFile)

    def addCallback(self, callback):
        self.callbacks.append(callback)

    def removeCallback(self, callback):
        self.callbacks.remove(callback)
        
    def checkFile(self):
        mtime = os.stat(self.filename)[stat.ST_MTIME]
        if mtime > self.mtime:
            self.mtime = mtime
            for callback in self.callbacks:
                callback(self.filename, mtime)
        reactor.callLater(self.period, self.checkFile)


if __name__=='__main__':

    import time

    def changed(filename, mtime):
        print "%s modified at %s." % (filename, time.ctime(mtime))
        
    open('/tmp/foo', "w").close()
    FileWatcher(0.1, '/tmp/foo').addCallback(changed)
    reactor.run()

Run it in one terminal window, and in the other run

  touch /tmp/foo

to see what happens.